1. Field of the Invention
The present invention relates to a marking device and a marking method for marking a production number, a product name, or the like, on a surface of component made of metal, synthetic resin or the like.
2. Description of the Related Art
As a marking device according to an earlier development, which is disclosed in, for example, the Japanese Patent Publication No. Tokukou-hei 3-27397, a marking device having a pressure adjusting mechanism for making a marking depth uniform without depending on a slant or a curvature of a surface to be processed, by applying a constant air pressure to a pressurizing rod with a pressure regulator, has been known.
Further, there is a marking device which is operated as follows. When a line to be marked on a surface is not continuous or when a marking portion moves between two positions in which each character is marked on a surface, the marking portion is separated from the surface to be processed, by a reciprocating mechanism part. After the marking portion moves to the next marking position in two-dimensional directions, the marking portion moves to the surface to be processed, by the reciprocating mechanism part, to mark the next character.
However, in the marking device disclosed in the Japanese Patent Publication No. Tokukou-hei 3-27397, in order to keep the constant pressure to be applied to the pressurizing rod, it was necessary to adjust a moving speed of a pen which was attached to an end of the pressurizing rod and a pressing force of the pen by changing the pressure setting value of the pressure regulator by hand or by setting a velocity adjusting valve to an inlet or an outlet of a feed pipe for compressed air. Because it is necessary to adjust the pressure to be applied to the pressurizing rod in accordance with the characteristics of an object to be marked, such as material, shape, hardness and the like, it takes a lot of time and labor to adjust the pressure.
In order to automatically adjust the pressure, it is necessary to provide a pressure sensor for detecting a pressing force of the pen and to automatically adjust a velocity adjusting valve which is set to the inlet or the outlet of the feed pipe for compressed air and a pressure regulator. However, when the structure of the device becomes complicated and the size of the device becomes large, the product cost of the device becomes higher. Because the air for adjusting the pressure is compressed fluid, the air pressure control has a poor response. As a result, it is difficult to automatically control the air pressure.
Further, in case that a plurality of characters or the like are marked on the object, when a line to be marked is not continuous, or when the marking portion moves between two positions in which each character is marked, it takes a lot of time to separate the marking portion from the surface to be processed, or to bring the marking portion into contact with the surface to be processed. There is a problem that the separating and bringing operations account for much of the whole marking time.
In order to solve the above-described problems, an object of the present invention is to provide a marking device and a marking method, in which the pressing force to be applied to the object to be marked, can be automatically controlled by a cheap and simple structure, and in which time for moving the marking portion when a line to be marked is not continuous or when two characters are apart from each other, can be shortened in order to shorten the whole marking time.
That is, in accordance with one aspect of the present invention, a marking device (for example, a marking device 10 shown in FIG. 1) comprises:
a marking mechanism (for example, a reciprocating mechanism part 1 shown in FIG. 1) for marking a surface to be processed, of an object to be marked, by reciprocating a marking portion (for example, a stylus 1g shown in FIG. 1):
a marking portion moving mechanism (for example, a two-dimension positioning mechanism part 3 shown in FIG. 1) for moving the marking portion in two-dimensional directions along the surface to be processed; and
a pressure adjusting circuit (for example, a pressure control circuit 2 shown in FIG. 1) for keeping a constant pressure which the marking portion applies to the surface to be processed;
wherein the marking mechanism comprises a cam mechanism for linearly reciprocating the marking portion by following a cam which is rotated by a driving member (for example, a motor 1a shown in FIG. 1).
According to one aspect of the present invention, because the pressing force applied to the object to be marked is directly detected by utilizing the reactive force from the marking portion, and the pressing force can keep constant, the marking device can adjust the pressure with a simple and small structure.
The marking device may further comprise a contact detecting circuit (for example, a current detecting resistance 28 shown in FIG. 4) for detecting a contact between the surface to be processed and the marking portion by a change in a value of a current flowing into the driving member;
wherein when the contact between the surface to be processed and the marking portion is detected by the contact detecting circuit, the pressure adjusting circuit (for example, a pressure control circuit 2 shown in FIG. 1) adjusts the pressure which is applied to the surface to be processed, in accordance with the change in the value of the current.
Therefore, the marking device can mark a character or the like on the object to be marked, by moving the marking portion at the most suitable speed and with the most suitable pressing force in accordance with the weight of the marking mechanism or the contact position of the surface to be processed.
In accordance with another aspect of the present invention, a marking method comprises the steps of:
marking a surface to be processed, of an object to be marked, by following a cam which is rotated by a driving member to reciprocate a marking portion;
moving the marking portion in two-dimensional directions along the surface to be processed;
detecting a contact between the surface to be processed and the marking portion by a change in a value of a current flowing into the driving member; and
keeping a constant pressure which the marking portion applies to the surface to be processed in accordance with the change in the value of the current, when the contact between the surface to be processed and the marking portion is detected in the detecting step.
The marking device may further comprise a warning output circuit (for example, an amplifier 29 shown in FIG. 4) for outputting a warning when the contact between the surface to be processed and the marking portion is not detected by the contact detecting circuit while the marking mechanism (for example, a reciprocating mechanism part 1 shown in FIG. 1) linearly reciprocates the marking portion.
The marking method may further comprise a step of outputting a warning when the contact between the surface to be processed and the marking portion is not detected in the detecting step while the marking portion is linearly reciprocated in the marking step.
Because a user can soon recognize that the marking mechanism is in a position that the marking portion cannot mark a character or the like on the object to be marked, it is possible to shorten marking time and to save the power.
The marking mechanism (for example, a reciprocating mechanism part 1 shown in FIG. 1) may comprise a cam having a cam curvature so that a torque which is applied to the driving member by the contact between the marking portion and the surface to be processed, is kept constant without depending on a position of the contact of the surface to be processed.
Because the torque applied to the driving member keeps constant, it is possible to mark a character or the like in a uniform depth without depending on the contact position that the marking portion is in contact with the surface to be processed.
In accordance with another aspect of the present invention, a marking device (for example, a marking device 10 shown in FIG. 1) comprises:
a marking mechanism (for example, a reciprocating mechanism part 1 shown in FIG. 1) for marking a surface to be processed, of an object to be marked, by reciprocating a marking portion (for example, a stylus 1g shown in FIG. 1) of which an end is vibrated;
a marking portion moving mechanism (for example, a two-dimension positioning mechanism part 3 shown in FIG. 1) for moving the marking portion in two-dimensional directions along the surface to be processed; and
a pressure adjusting circuit (for example, a pressure control circuit 2 shown in FIG. 1) for keeping a constant pressure which the marking portion applies to the surface to be processed;
wherein the pressure adjusting circuit weakens the pressure which is applied to the surface to be processed, and stops vibrating the end of the marking portion, when a line to be marked is not continuous or when the marking portion moves between two positions in which each character is marked on the surface to be marked; and
the marking portion moving mechanism moves the marking portion to a next position to be marked in the two-dimensional directions.
In accordance with another aspect of the present invention, a marking method comprises the steps of:
marking a surface to be processed, of an object to be marked, by reciprocating a marking portion of which an end is vibrated;
weakening a pressure which is applied to the surface to be processed, to keep the pressure constant, and stopping vibrating the end of the marking portion, when a line to be marked is not continuous or when the marking portion moves between two positions in which each character is marked on the surface to be marked; and
moving the marking portion to a next position to be marked in two-dimensional directions.
According to another aspect of the present invention, when a line to be marked is not continuous, or when the marking portion moves between two positions in which each character is marked, the marking portion hardly reciprocates. Therefore, it is possible to dramatically shorten time for the marking. Further, because time for operating the marking mechanism is shortened, it is possible to improve the durability of the marking mechanism. Therefore, the possibility of the breakdown can be improved.
In accordance with another aspect of the present invention, a marking device comprises:
a marking portion moving mechanism for moving a marking portion;
a reciprocating mechanism for reciprocating the marking portion;
a pressure control circuit for controlling a pressure which a marking portion applies to a surface to be marked; and
wherein when the marking portion moving mechanism moves the marking portion without marking the surface to be marked, the reciprocating mechanism stops reciprocating the marking portion, the pressure control circuit weakens the pressure so as to hardly mark the surface to be marked, and the marking portion is moved along the surface to be marked.
In accordance with another aspect of the present invention, a marking method comprises the steps of:
moving a marking portion;
reciprocating the marking portion;
controlling a pressure which a marking portion applies to a surface to be marked; and
wherein when the marking portion is moved without marking the surface to be marked, the marking portion stops being reciprocated, the pressure is weakened so as to hardly mark the surface to be marked, and the marking portion is moved along the surface to be marked.